In the past, very small wires were always very difficult to install properly using an automated process. The main challenge is to adequately position the wire, attach it properly and then cut it at the right location. A further challenge is to keep the tension in the wire within an appropriate range, especially in the case of wires achieving a mechanical function. Examples of such wires are the ones used as micro actuator mechanisms. These micro actuator mechanisms are useful in many applications, such as in very small mechanical relays, sensors, flow controllers, valves, etc. Micro actuator mechanisms used in these applications typically use heat-shrinkable wires to achieve movement of internal mechanical structures performing various functions. An example of heat-shrinkable material is a Nickel-Titanium alloy. In the case of a relay application, the heat shrinkable wire is used to open and close contacts of the relay. This wire replaces conventional actuators, such as electromagnetic actuators, electro-static actuators, bimetallic actuators, etc. The advantage of this new mate rial is that it enables significant size and cost reduction if an automated manufacturing process is available for mass production. The wire is attached to a mechanical structure that moves when the wire shrinks or expands back to its original size. This movement enables the closing and opening of the relay contacts. Such relays are opened or closed using a control voltage applied at both ends of the wire, thereby allowing a current to flow through the wire and heat it above its transition temperature. This property of the wire is what moves the electrical contacts in or out of engagement. These relays can have only a few millimeters in size. Consequently, large numbers of these relays can be provided on a single printed circuit board (PCB). A typical use for such hardware is for telecommunications.
The Nickel-Titanium alloy wire is a very difficult wire to handle. It is a very rigid and ductile wire that can not be bonded using traditional method like thermosonic, ultrasonic, weld, etc. Therefore, this wire needs to be mechanically attached using a mechanical attachment point hereby referred to as a “crimp”. A further challenge is thus to be able to handle such difficult material when used in very small parts, especially when using very small lengths of wire with very small diameters. There is always a need for more compact designs that are less expensive, whether it is for a new relay or a micro pump to be used by the medical industry. In order to achieve this task, the manufacturing equipment need to be extremely precise and able to handle the wire very gently, so they do not alter its behavior, while being very fast to enable cost effectiveness. Such equipment did not exist.
Considering this background, it clearly appears that there was a need to develop a new apparatus for installing a length of wire between two crimps, in particular an apparatus capable of handling a delicate wire made of a material difficult to handle.